Prior to setting forth the background of the related art, it may be helpful to set forth definitions of certain terms that will be used hereinafter.
The term “cellular communication network” as used herein in this application, is defined as any radio frequency (RF) based communication network that is based upon geographical partition of space into cells. Each cell is provided with at least one base station that manages the wireless communication therein. Various cellular communication standards are currently in use while other are being developed. The popular ones are: UMTS, HSPA, GSM, CDMA-2000, TD-SCDMA, LTE and WiMAX.
The term “Universal Mobile Telecommunications System” or “UMTS” as used herein in this application, is one of the third-generation (3G) cell phone technologies, which is also being developed into a 4G technology. Currently, the most common form of UMTS uses Wideband Code Division Multiple Access (W-CDMA) as the underlying air interface. W-CDMA is a wideband spread-spectrum mobile air interface that utilizes the direct-sequence spread spectrum method of asynchronous code division multiple access to achieve higher speeds and support more users compared to the implementation of time division multiplexing (TDMA) used by 2G GSM networks.
The term “Macrocell” as used herein in this application, also known as Macrocell Base Station (MBS) is defined as a cell in a mobile phone network that provides radio coverage served by a power cellular base station (e.g. tower). The antennas for macrocells are usually mounted on ground-based masts, rooftops and other existing structures, at a height that provides a clear view over the surrounding buildings and terrain. Macrocell base stations have power outputs of typically few watts to tens of watts.
The term “Femtocell” as used herein in this application, is the industry term for a small cellular communication base station, typically designed for use in residential, enterprise or small business environments. The femtocell connects to the service provider's network via broadband Ethernet connection (such as DSL or cable). Current designs typically support two to five mobile phones simultaneously in a residential setting. A femtocell allows service providers to extend service coverage and capacity indoors, especially where access would otherwise be limited or unavailable. The femtocell incorporates the functionality of a typical base station but extends it to allow a simpler, self contained deployment. By way of example, a UMTS femtocell may contain a Node B, RNC and GSN with Ethernet connection for backhaul.
The terms “Microcell” and “Picocell” as used herein in this application are the industry terms used to describe cells in a mobile phone network served by a low power cellular base station, covering a limited area such as a mall, a hotel, train station or an aircraft. A microcell is usually larger than a picocell, though the distinction is not always clear. Both microcells and picocell use power control to limit the radius of their coverage area. Typically a microcell is approximately a kilometer wide and a picocell covers a few hundred meters.
FIG. 1 shows a high level schematic block diagram of a cellular communication base station incorporating a base band processor according to the prior art. Femtocell base station 10 usually comprises a single digital base band processor 12 that is connected to an RF unit 18, a 10/100 Ethernet physical layer 20, a flash based storage 16, and an SRAM memory 14. RF unit 18 comprises an antenna through which communication between femtocell base station 10 and a plurality of cellular communication enabled devices (hereinafter “user equipment” or “UE”) 50A-50C is established. Base band processor 12 connects to mobile operator network 40 via Ethernet physical layer 20 and gateway 30.
In operation, base band processor 12 is arranged to manage the RF communication traffic with plurality of UE 50A-50C and simultaneously manage the Ethernet backhaul with mobile operator network 40. The number of UE as well as other properties of femtocell base station 10 depends on the processing power of base band processor 12.
One of the challenges of the evolving cellular communication base stations technology is to provide cost effective coverage of the cellular communication network given the users traffic requirements and the physical layout constraints. A base station within a cellular network is regarded cost effective in view of the ratio between the number of users supported by it and the cost of the processor(s) that are required to implement it.
Specifically, cost effective deployment of base stations and the ability to provide the most suitable type of base station, be it femtocell, picocell or microcell is much affected by the cost flexibility of each type of base station.
It would be therefore advantageous to provide a solution for cost effective provision of variable performance base stations that differ in coverage area and processing power and yet provide all of the required functionalities of cellular communication networks.